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230 | cejka | 1 | /* |
2 | * Copyright (C) 2005 Josef Cejka |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | #include <arch/fmath.h> |
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30 | #include <print.h> |
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31 | |||
32 | #define FMATH_MANTISA_MASK ( 0x000fffffffffffffLL ) |
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33 | |||
34 | int fmath_is_negative(double num) |
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35 | { |
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36 | fmath_ld_union_t fmath_ld_union; |
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37 | fmath_ld_union.bf = num; |
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38 | return ((fmath_ld_union.ldd[7])&0x80)==0x80; /*first bit is sign, IA32 is little endian -> 8th byte*/ |
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39 | |||
40 | } |
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41 | |||
42 | signed short fmath_get_binary_exponent(double num) |
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43 | { |
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44 | fmath_ld_union_t fmath_ld_union; |
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45 | fmath_ld_union.bf = num; |
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46 | return (signed short)((((fmath_ld_union.ldd[7])&0x7f)<<4) + (((fmath_ld_union.ldd[6])&0xf0)>>4)) -FMATH_EXPONENT_BIAS; /* exponent is 11 bits lenght, so sevent bits is in 8th byte and 4 bits in 7th */ |
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47 | } |
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48 | |||
49 | double fmath_get_decimal_exponent(double num) |
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50 | { |
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51 | double value; |
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52 | /* log10(2)*log2(x) => log10(x) */ |
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53 | __asm__ __volatile__ ( \ |
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54 | "fldlg2 #load log10(2) \n\t" \ |
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55 | "fxch %%st(1) \n\t" \ |
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56 | "fyl2x #count st(0)*log2(st(1))->st(1); pop st(0) \n\t" \ |
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57 | : "=t" (value) : "0"(num) ); |
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58 | return value; |
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59 | } |
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60 | |||
61 | __u64 fmath_get_binary_mantisa(double num) |
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62 | { |
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63 | union { __u64 _u; double _d;} un = { _d : num }; |
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64 | un._u=un._u &(FMATH_MANTISA_MASK); /* mask 52 bits of mantisa*/ |
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65 | return un._u; |
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66 | } |
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67 | |||
68 | double fmath_fint(double num, double *intp) |
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69 | { |
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70 | fmath_ld_union_t fmath_ld_union_num; |
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71 | fmath_ld_union_t fmath_ld_union_int; |
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72 | signed short exp; |
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73 | __u64 mask,mantisa; |
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74 | int i; |
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75 | |||
76 | exp=fmath_get_binary_exponent(num); |
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77 | |||
78 | if (exp<0) { |
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79 | *intp = 0.0; |
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80 | *intp = fmath_set_sign(0.0L,fmath_is_negative(num)); |
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81 | return num; |
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82 | } |
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83 | |||
84 | |||
85 | if (exp>51) { |
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86 | *intp=num; |
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87 | num=0.0; |
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88 | num= fmath_set_sign(0.0L,fmath_is_negative(*intp)); |
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89 | return num; |
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90 | } |
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91 | |||
92 | fmath_ld_union_num.bf = num; |
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93 | |||
94 | mask = FMATH_MANTISA_MASK>>exp; |
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95 | //mantisa = (fmath_get-binary_mantisa(num))&(~mask); |
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96 | |||
97 | for (i=0;i<7;i++) { |
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98 | /* Ugly construction for obtain sign, exponent and integer part from num */ |
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99 | fmath_ld_union_int.ldd[i]=fmath_ld_union_num.ldd[i]&(((~mask)>>(i*8))&0xff); |
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100 | } |
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101 | |||
102 | fmath_ld_union_int.ldd[6]|=((fmath_ld_union_num.ldd[6])&(0xf0)); |
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103 | fmath_ld_union_int.ldd[7]=fmath_ld_union_num.ldd[7]; |
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104 | |||
105 | *intp=fmath_ld_union_int.bf; |
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106 | return fmath_ld_union_num.bf-fmath_ld_union_int.bf; |
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107 | }; |
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108 | |||
109 | double fmath_set_sign(double num,__u8 sign) |
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110 | { |
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111 | fmath_ld_union_t fmath_ld_union; |
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112 | fmath_ld_union.bf = num; |
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113 | fmath_ld_union.ldd[7]=((fmath_ld_union.ldd[7])&0x7f)|(sign<<7); /* change 64th bit (IA32 is a little endian)*/ |
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114 | return fmath_ld_union.bf; |
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115 | } |
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116 | |||
117 | double fmath_abs(double num) |
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118 | { |
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119 | return fmath_set_sign(num,0); |
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120 | } |
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121 | |||
122 | double fmath_dpow(double base, double exponent) |
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123 | { |
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124 | double value=1.0; |
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125 | if (base<=0.0) return base; |
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126 | |||
127 | //2^(x*log2(10)) = 2^y = 10^x |
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128 | |||
129 | __asm__ __volatile__ ( \ |
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130 | "fyl2x # ST(1):=ST(1)*log2(ST(0)), pop st(0) \n\t " \ |
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131 | "fld %%st(0) \n\t" \ |
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132 | "frndint \n\t" \ |
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133 | "fxch %%st(1) \n\t" \ |
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134 | "fsub %%st(1),%%st(0) \n\t" \ |
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135 | "f2xm1 # ST := 2^ST -1\n\t" \ |
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136 | "fld1 \n\t" \ |
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137 | "faddp %%st(0),%%st(1) \n\t" \ |
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138 | "fscale #ST:=ST*2^(ST(1))\n\t" \ |
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139 | "fstp %%st(1) \n\t" \ |
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140 | "" : "=t" (value) : "0" (base), "u" (exponent) ); |
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141 | return value; |
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142 | } |
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143 |